Table of Content

25 August 2004, Volume 25 Issue 4

Previous Issue    Next Issue

Problem and advance on the fluid typing for complex reservoirs using well log

Li Zhoubo

2004, 25(4):  356-362.  doi:10.11743/ogg20040401

Asbtract ( 666 )   PDF (7160KB) ( 449 )  

References | Related Articles | Metrics

The difference of physical parameters in oil-gas-water are premise that geophysical well log can be used for fluid typing. However, the identification of oil-gas-water layers is also dependent on lithology and pore structure of reservoir rocks. Porosity index M is an important parameter when electrical resistivity is used for the fluid typing of reservoir rocks with complex pore structure. The M value may be estimated by the micro-resistivity imaging logs, combined with conventional porosity logs. Low-resistivity reservoirs are caused by different reasons, therefore the different methods are needed for their fluid typing. The improved data collection pattern is suitable for a thin-interbedded reservoir; the improved interpretation model is suitable for the low-resistivity reservoirs caused by pore structure and mud content. In recent years, some progresses have been made in fluid typing using NMR logs. On the basis of original differential spectra, many new methods, such as time-domain analysis method, mobile spectra method, diffusion-forcing method and diffusion-editing method, have been successively developed and improved.

Some issues on China's petroleum resource potential

Qian Ji

2004, 25(4):  363-369.  doi:10.11743/ogg20040402

Asbtract ( 873 )   PDF (7517KB) ( 415 )  

References | Related Articles | Metrics

Some major issues of China's oil industry,such as China's petroleum resource potential,medium-long term oil demand and present petroleum exploration stage, have been discussed by various methods. Their results indicate that the discovery maturity (percentage of ultimately proven reserve with respect to total resources) of China's petroleum resources is very low, oil exploration remains in peak discovery stage but gas exploration is still in early discovery stage. The forecast result of oil and gas demand will be made with a large error if it is conducted only using a single factor at a certain period, such as consumption index and GDP growth correlation coefficient. By the end of 2020, the newly-added proven reserves in place in China would reach 160-200 million tons for oil and 8-10 billion m³ for natural gas respectively; the percentage of import oil in China's total consumption should not exceed 40%. It is estimated that the China's recoverable oil resource is 260 million tons or more. In China, the main contradiction of petroleum resource demand is reflected in a great resource potential and slow resource discovery rate. The top priority task at present is accelerating petroleum discovery rate, cutting down the energy consumption, and adjusting the energy source composition. Therefore, the government should issue the relevant policies and lows of encouraging petroleum discovery and adjusting energy consumption; the oil company should continue increasing the exploration activities in frontier areas, improving the discovery rate and exploration maturity of petroleum resources, and raising the percentage of domestic oil and gas productions in total consumption, in order to reduce the pressure brought by the high percentage of import oil and to ensure the safety of national petroleum strategy.

Prediction method and its preliminary application in predicting resource potentials of subtle oil/gas reservoirs

Pang Xiongqi, Chen Dongxia, Li Pilong, Jiang Zhenxue, Haofang

2004, 25(4):  370-376.  doi:10.11743/ogg20040403

Asbtract ( 736 )   PDF (7131KB) ( 457 )  

References | Related Articles | Metrics

As formation, evolution and genetic mechanism of subtle oil/gas reservoirs are very complicated, various methods, such as discovery process model inversion, theoretical forward computation of hydrocarbon accumulation threshold and comprehensive prediction method, should be comprehensively used, so as to increase the reliability of potential evaluation and provide scientific basis for high level decision-makers. These methods are used to predict the potentials of subtle reservoirs in Jiyang depression. The prediction results show that there are still more than 2.024 billion tons reserves to be discovered in subtle reservoirs in the depression, which account for over 75% of the remaining provable reserves. The undiscovered possible reserves in subtle reservoirs in Dongying, Zhanhua, Chezhen and Huimin sags are 783 million tons, 353 million tons, 378 million tons and 352 million tons respectively. Laterally, subtle oil/gas reservoirs are mainly distributed in the reservoiring systems having relatively high abundance of reserves and relatively low proved reserves. Vertically, although the 4^th member of Shahejie Formation and the targets above it have highly been explored, they are still the key horizons for discovering new reserves in subtle reservoirs. Lithologic lenticular reservoir, unconformity-screened reservoir and buried hill reservoir are the main types of subtle reservoirs to be explored in the future.

Possible chemical constitutions and original biological materials of various vitrinites in coal measure strata

Liu Dayong, Peng Ping'an

2004, 25(4):  377-384.  doi:10.11743/ogg20040404

Asbtract ( 725 )   PDF (8559KB) ( 381 )  

References | Related Articles | Metrics

Chemical constitutions of vitrinites in Jurassic coal measures in eastern Junggar basin and Turpan-Hami basin,and Permo-Carboniferous coal measures in Ordos basin,are studied through solid-state ¹³C NMR and transient pyrolysis-GC/MS. The aliphatic carbons in Jurassic hydrogen-rich desmocollinites have relatively high proportion of methylene carbon(-CH₂-),and the proportion of aliphatic hydrocarbons in pyrolysis products are relatively high. Being compared with desmocollinites, although the Jurassic telocollinites are also hydrogen-rich, their aliphatic carbons have even higher proportion of methyl(-CH₃),methine(-CH-) and quaternary carbon, and their pyrolysis products are mainly phenols and alkylbenzenes, with more branched substitiuents but shorter chain length. Though the Permo-Carboniferous vitrinites in Ordos basin are mostly composed of desmocollinites, they contain a relatively small proportion of aliphatic carbons, and most of which are gas-prone carbons. The pyrolysis products are mainly phenols and aromatic hydrocarbons, thus they are typical gas source rocks. With similar maturities, the structures of vitrinites are determined by sedimentary environments and original bilological materials. Ultramicroliptinites might have contributed to the relatively high constitutions of long chain aliphatic hydrocarbons in hydrogen-rich vitrinites in eastern Junggar and Turpan-Hami basins. Based on comparison with pyrolysis products of phycoplast,cutinites, sporinites and suberinite, and in combination with other evidences, it is believed that exinites of higher plants are more likely to be the main components of Ultramicroliptinites.

Comparison of enrichment patterns of various energy resources in Ordos basin

Wei Yongpei, Wang Yi

2004, 25(4):  385-392.  doi:10.11743/ogg20040405

Asbtract ( 717 )   PDF (8556KB) ( 480 )  

References | Related Articles | Metrics

Ordos basin is prolific in oil, gas, coal and uranium resources. Vertically, oil, coal and uranium distribute mainly in Jurassic, while gas distributes mainly in Permian and Ordovician; natural gas is located below oil and uranium, and closely above and/or below the Permo-Carboniferous coal measures. Laterally, oil distributes in the central and southern ports of the basin, uranium deposits are located in the northern and western edges of the basin, natural gas and coal distribute in the whole basin, and recoverable coals distribute in the basin margin. Gas distributions in Lower and Upper Paleozoic have been controlled by the palaeokarsts formed in the late Caledonian to Hercynian fossil weathered crusts, and the widely distributed large braided river delta front sediments, respectively. The accumulation of coal has been controlled by the turning stage of tectonism and palaeoclimate, and the enrichment of uranium has been controlled by oxidation-reduction environment. The minerogenic evolutions of various energy resources in the basin are characterized by their obvious phasic development, and the commercial energy resources have been accumulated in a sequence of coal→uranium→gas→oil. Yishan slope area is favorable for exploration of oil, gas,coal and unconventional gas; Tianhuan depression and the thrust belts on the western edge of the basin are favorable for joint exploration of oil, gas,coal and uranium;Yimeng uplift and Weibei and Jinxi flexural fold belts are favorable for joint exploration of coal, coalbed methane and uranium.

Formation conditions and distribution of lithologic pools in Songliao basin

Yang Yufeng

2004, 25(4):  393-399.  doi:10.11743/ogg20040406

Asbtract ( 745 )   PDF (8290KB) ( 401 )  

References | Related Articles | Metrics

Thin sandstone and mudstone interbed, deposited in lacustrine river-deltaic enviroment, is the necessary geologic condition of lithologic pool formation in the large, shallow-middle seated depressions, Songliao basin. Since the sedimentary accommodation, caused by the changes of base level, has a great difference in geologic time, the types of sand body have vertically a certain difference. Because the buried depth of reservoir rocks and relative position of reservoir rocks with source rocks are various, the formation condition and distribution of lithologic pools have also a certain difference in different plays. Fault plays an important role in the formation of lithologic pools, which is not only the basic attribute in the formation of composite fault-lithologic trap but also the major migration path of oil and gas into lithologic pools. In the areal extent, types of lithologic pool are controlled by structure position and sand body development. The lithologic pools are mainly developed in the delta-frontal facies belt in the large depressions, whereas the subtle oil and gas pools are mainly distributed in the periphery of the depressions.

Hydrocarbon-generating potential and history of Carboniferous-Permian coal measure strata in Wenliu area

Xu Huazheng, Zhou Xinke

2004, 25(4):  400-407,421.  doi:10.11743/ogg20040407

Asbtract ( 808 )   PDF (8900KB) ( 394 )  

References | Related Articles | Metrics

The Carboniferous-Permian coal measure strata in Dongpu sag is a fair source rock unit of Wenliu gas pool due to its stable distribution and high organic content. There are two hydrocarbon-generating periods in the burial history of coal measures. The first one occurs when the T_1-2 formation is deposited. Vitrinite reflectance, apatite fission track and fluid inclusion analyses indicate that the burial depth of coal measures is about 3500 m, with the palaeotem-perature of 118℃ and R_o of 0.80%-0.85%.Hydrocarbon generation of coal measures was interrupted in the Meso-zoic uplift and erosion period (about 1.8 million years).During the Paleogene rifting period,the coal measures was entered into its secondary hydrocarbon-generating period as the burial depth increases, reaching its hydrocarbon-generating peak after the deposition of Dongying formation. The gas-prone source rock is mainly distributed in the region of Wendong-Qianliyuan, with the buried depth of 5290-6360m. The discovery maturity (percentage of ultimately proven reserve with respect to total resources) of gas resources in Wenliu area is more than 90%. In the effective gas supply area of Wenliu gas pool, the hydrocarbon-generating volume and hydrocarbon-expelling volume of Carboniferous-Permian coal measures are estimated to be 3253.3 million m³ and 2657.0 million m³ respectively, with a gas accumulation coefficient of 5.92%.

Non-structural reservoirs in northern shelf basins of South China Sea

Zhu Weilin, Wang Zhenfeng, Zhang Yingzhao

2004, 25(4):  408-415.  doi:10.11743/ogg20040408

Asbtract ( 731 )   PDF (8824KB) ( 579 )  

References | Related Articles | Metrics

The northern shelf basins of South China Sea have the favorable conditions for the formation of non-structural reservoirs. In the geological history, frequent sea level fluctuations resulted in both vertical and lateral lithologic variations, leading to the formation of lithologic reservoirs, especially the low-level fans deposited on both the basin floor and slope during the lowstand. Frequent tectonic movements in the geological history resulted in many structural planes and structural unconformities, and so various types of unconformity reservoirs had correspondingly been formed. Exploration practices and research achievements show that the potential areas for non-structural reservoirs in offshore basins are as follows:(1) deep water areas where submarine fans are well developed, such as the central depression in Qiongdongnan basin, and Baiyun sag in Zhujiangkou basin; (2)frontal areas of large paleodeltas, such as Yingdong slope zone in Yinggehai basin and Yacheng 13-1 structural zone in Qiongdongnan basin; (3)sandbodies developed on the shelf, slope and basin floor around the diapiric structures in Yinggehai basin.

Formation and distribution of subtle reservoirs in northern steep slope zone of Dongying depression

Li Sumei, Pang Xiongqi, Qiu Guiqiang, Gao Yongjin, Sun Xinian

2004, 25(4):  416-421.  doi:10.11743/ogg20040409

Asbtract ( 770 )   PDF (6714KB) ( 547 )  

References | Related Articles | Metrics

Various types of subtle reservoirs are developed in the northern steep slope zone of Dongying depression during different periods. During fault subsidence, various lithologic reservoirs and relevant compound reservoirs, including lenticular reservoirs, structural-lithologic reservoirs and updip pinch out reservoirs, are developed. During the transitional period from fault subsidence to downwarping, stratigraphic reservoirs as well as lithologic and structural reservoirs controlled by stratigraphy are developed, including unconformity reservoirs, fault-lithologic reservoirs, strati-graphic overlap-fault reservoirs, and fault-lithologic and stratigraphic reservoirs controlled by unconformities. Various types of hydrocarbons accumulated in different subtle reservoirs. On the periphery of the northern steep slope zone, hydrocarbons accumulated in the structure-controlled stratigraphic-lithologic reservoirs in the 3^rd member of Shahejie Formation that have been formed during fault subsidence period, and in the stratigraphic reservoirs formed during the transitional period from fault subsidence to downwarping have mainly been sourced from the 4^th member of Shahejie Formation. While in the inner part near hydrocarbon-generating center, hydrocarbons accumulated in the lenticular lithologic reservoirs and other lithology-related reservoirs in the 3^rd member of Shahejie Formation, and fault-lithologic reservoirs in the upper part of the 3^rd member of Shahejie Formation have mainly been sourced by the source rocks in the 3^rd member of Shahejie Formation. The formation of subtle reservoirs and the distributional characteristics of petroleum have been controlled by various factors, such as paleo-tectonic setting, hydrocarbon migration pathways, combination of source, reservoir and cap rocks, and the timing of hydrocarbon generation and accumulation.

Significance of slope break zones in downwarped lake basins to exploration of non-structural traps in Junggar basin

Liu Hao, Wang Yingmin

2004, 25(4):  422-427.  doi:10.11743/ogg20040410

Asbtract ( 795 )   PDF (6351KB) ( 636 )  

References | Related Articles | Metrics

Multistage slope break zones which are well developed on the northwestern edge of Junggar basin significantly control the development of sequence stratigraphy, overlapping and superimposition of strata, vertical lithologic combinations and vertical and lateral distribution of sediments. The control of multistage slope break zones on non-structural traps are mainly represented as follows:1) Non-structural traps are developed closely near the multistages slope break zones, and distributed in beaded occurrence along the slope break zones. 2) The development of non-structural traps is vertically characterized by their inheritance. 3) The types of non-structural traps vary with the geographical positions of the slope break zones. Non-structural traps would mainly be developed as stratigraphic overlaps and truncations in the slope break zone near basin edges, stratigraphic traps would gradually decrease basinward and then mainly become stratigraphic-lithologic or lithologic traps. The existence of multistage slope break zones would correspondingly lead to various erosions and depositions at different geographical positions in the basin, and control the combination of reservoirs and seals in non-structural traps. In addition, fractures developed in faulted slope break zones and fissures developed in flexural slope break zones would act as migration pathways, and would be favorable to hydrocarbon migration and accumulation. The structures deeply buried in the slope break zones would often be advantageous to hydrocarbon accumulation, thus the slope break zones would also be the favorable sites for accumulation of hydrocarbons that migrate vertically upward and redistribute from the earlier hydrocarbon accumulations at depth.

A brief talk on gas exploration potential in the platform-basin region,Tarim basin

Yun Lu, Xiao Zhigao, Xu Mingjun

2004, 25(4):  428-432.  doi:10.11743/ogg20040411

Asbtract ( 715 )   PDF (5487KB) ( 696 )  

References | Related Articles | Metrics

Tarim basin is a huge superposed basin composed of Paleozoic cratonic basin and Meso-Cenozoic foreland basin. The main factors that control the gas accumulation in the cratonic basin are (1) thick source rocks and prolonged low-geotemperature field, which are an important conditions for prolonged hydrocarbon generation and multiphase gas accumultion; (2) palaeohigh and palaeoslope, which control the hydrocarbon migration and accumulation in Paleozoic marine strata; (3) palaeokarst reservoir, which provides reservoir space for the large oil and gas fields in paleozoic carbonate rocks; (4) Paleozoic non-structural trap, which is the main trap type of large oil and gas fields; (5) evolution of closed system of oil and gas accumulation, which controls the distribution of oil and gas resource and its exploration strategy. The condensate reservoir in the ninth block of Tahe oilfield and Hetian river gas field are selected as two examples that illustrate the gas accumulation in cratonic basin. The characteristics of hydrocarbon-generating period of main source rocks indicate that there is a better conditions of gas accumulation in the uplifted belts around the Paleozoic cratonic basin. The potential reservoir rocks near the early Paleozoic source rock are the important targets of gas exploration. Therefore, in Bachu-Maigaiti region and peripheral areas of Manjiaer depression, the exploration activity of mature and overmature gas exploration in marine strata should be increased.

Reservoiring factors of large structural - lithologic composite oil reservoir in Biyang depression

Qin Weijun

2004, 25(4):  433-436.  doi:10.11743/ogg20040412

Asbtract ( 748 )   PDF (3709KB) ( 717 )  

References | Related Articles | Metrics

Shuanghe oilfield in Biyang depression is one of the large structural-lithologic composite oil reservoirs in eastern China. Cumulative proved oil reserves in place have reached 101.76 million tons by the end of 2001 since overall exploration and development began in 1977. This oilfield has rich source rocks, well-developed sandbodies, good migration pathways, favorable matching of trap formation and sandbodies, and superior preservation conditions, all of which are favorable for hydrocarbon accumulation. Along with the formation and evolution of Shuanghe nose structure, sandbodies in the 3^rd member of Hetaoyuan Formation in southern Biyang depression change gradually from downdipping pinch-out to upwarping pinch-out, leading to the formation of the small but prolific Shuanghe oilfield with large reservoir space and enough time for charging hydrocarbon.

Oil classification and biodegradation in Daerqi oilfield, Baiyinchagan depression

Tan Yuming, Feng Jianghui, Zhang Yunxian, Jin Guangxing, Pan Changchun, Sheng Guoying, Fu Jiamo

2004, 25(4):  437-443.  doi:10.11743/ogg20040413

Asbtract ( 768 )   PDF (6570KB) ( 704 )  

References | Related Articles | Metrics

Based on oil physical features, group compositions, biomarker compounds and biodegradation, the crude oil in the Daerqi oilfield is classified into five types.Type I oil is a low viscosity and density, light oil. Its group composition is predominately the saturated hydrocarbon, with a low contents of nonhydrocarbon and asphaltic components. This type of oil is unbiodegraded, with a high sterane isomerization index and maturity. Type Ⅱ oil is immature and extremely viscous, with a relatively high density. Its group composition is dominated by nonhydrocarbon and asphaltic components, with a low content of saturated hydrocarbon. This type of oil is unbiodegraded, with a low sterane isomerization index. Type Ⅲ oil is a mixed product of type I oil and type Ⅱ oil. Type Ⅳ oil is a common viscous oil, with a relatively high viscosity and density, which is formed by biodegradation of type I oil. Type V oil could be caused by biodegradation of type Ⅲ oil. Its density and viscosity are similar to that of type Ⅳ oil, but sterane isomerization index is relatively low. Excluding the type Ⅱ oil (immature and extremely viscous oil) from the shallow immature source rock of the Duhongmu Formation, all the oil of other four types are mainly derived from the higher mature, deep-seated source rocks of the Tenggeer Formation and/or A'ershan Formation.

Episodic expulsion of hydrocarbons in overpressured systems in Dongying depression

Chen Zhonghong, Zha Ming, Jin Qiang

2004, 25(4):  444-447,454.  doi:10.11743/ogg20040414

Asbtract ( 699 )   PDF (5827KB) ( 925 )  

References | Related Articles | Metrics

Source rocks in Dongying depression are characterized by rapid and continuous deposition and large thickness, as well as high heat flow, high geotherm and high content of organic matters. Large thickness of mudstones are developed in the main source rock intervals(3^rd and 4th members of Shahejie Formation). Source rocks are mainly deposited in the forms mudstone inlaid with sandstone, sandstone enclosed within mudstone and pure mudstones. As a result, overpressured systems are well developed in mature source rock intervals, and episodic expulsion becomes the fundamental mode of hydrocarbon expulsion in Dongying depression. The episodic expulsion of hydrocarbons in the overpressured systems in the depression can be classified into "tectonic episode" and "pressure episode".The mechanism of "tectonic episode" is destruction caused by tectonic activities, and hydrocarbons migrate along fault planes and tectoclase, while the mechanism of "pressure episode" is the accumulation and release of the "residual energy" in the overpressured systems, and hydrocarbons migrate along microfissures induced from fracturing. Hydrocarbon expulsion efficiency and hydrocarbon index in the overpressured systems with episodic expulsion are remarkably higher than that in the upper source rock interval, and they are remarkably lower than that in the lower source rock interval. Episodic expulsion of hydrocarbon has important significance in petroleum exploration, due to its characteristics of high energy and rapid migration.

A study on dynamic reservoiring process of hydrocarbon in lithologic reservoirs in Dongying depression

Wan Xiaolong, Qiu Nansheng, Zhang Shanwen

2004, 25(4):  448-451.  doi:10.11743/ogg20040415

Asbtract ( 723 )   PDF (4324KB) ( 507 )  

References | Related Articles | Metrics

Dynamic reservoiring process of hydrocarbon in Niu-35 and Ying-11 sandbodies in Dongying depression have been studied by using homogenization temperature of fluid inclusion, in combination with burial history and palaeogeothermal data. This paper systematically analyzes the evolution of source rocks, porosity and permeability evolution of sandsbodies, the time of hydrocarbons charging into the sandbodies, and the time of overpressure being formed on the basis of dynamic modeling of burial, thermal and hydrocarbon-charging histories. Based on comprehensive analysis, it is believed that a palaeotemperature of 90℃ and a palaeopressure of 17 MPa are favorable for the formation of lithologic reservoirs. Charging of large amount of hydrocarbons during-after reservoiring can lead to overpressured formations. sandbodies located in various reservoiring systems would have different fill factors and pressure coefficients. When sources of hydrocarbons are abundant, lenticular lithologic reservoirs with high fill factor and large pressure coefficient can be formed in deep and closed reservoiring systems, while lithologic reservoirs with moderate fill factor and relatively high pressure coefficient can be formed in half-open reservoiring systems.

Integrated development adjustment in Pucheng oilfield

Ren Yulin, Yuan Xiangchun, Liu Diyuan, Zhao Liangjin, Zhang Wangming

2004, 25(4):  452-454.  doi:10.11743/ogg20040416

Asbtract ( 774 )   PDF (3244KB) ( 447 )  

References | Related Articles | Metrics

Pucheng oilfield is in the development stage of extremly high water-cut, with the production decline rate of 27.36%.The main factors influencing development effect are:(1)a lot of commingled water injection and producing well; (2)severe damage of well network; (3)weak study of basic geology; and (4)the insufficient quantitative examination of remaining oil. Based on the forecast of production exponential decline model, oil production will be decreased to 800 thousand tons and water content will be increase to 96% in 2006, if the present development scheme is still used. In dealing with these probleums, the following measures have been proposed:(1)reconstruction of flooding pattern; (2)detailed division of flow unit and study of remaining oil distribution; (3)transition from zonal injection-commingled production into zonal injection and production; and (4)evaluation of the reserve difficult to produce.

A study of beach and bar sands subtle reservoirs in western slope of Qinan sag

Mao Ningbo, Fan Zheqing, Li Yuhai, Dai Tagen

2004, 25(4):  455-461.  doi:10.11743/ogg20040417

Asbtract ( 806 )   PDF (7065KB) ( 524 )  

References | Related Articles | Metrics

Comprehensive study of core, logging and seismic data, and classification of stratigraphic sequence interfaces show that various types of sandbodies, including beach and bar sands, coastal subaqueous fan and gravitational flow channel sands in Shahejie Formation, are developed on the western slope of Qinan sag. Basal overlapping, top denudation, and facies variation between them are evident in Shahejie Formation, thus multiple layer systems and various types of non-structural traps can be formed.The western slope in Qikou depression,an inherent structural slope,is the main directional area of hydrocarbon migration in the depression, and has excellent hydrocarbon supplying conditions. The beach and bar sandbodies in the 3 member of Shahejie Formation are widely distributed, and have an average porosity of 24.8% and average permeability of 175.5×10^-3μm²,thus belong to high porosity and high permeability reservoirs.Moreover, these sandbodies have never been disrupted by large tectonic movement since their sedimentation, thus the area would have favorable hydrocarbon preservation conditions. Various types of reservoirs have been discovered during previous exploration, including unconformity reservoirs, upwarping pinch-out reservoirs, and structural-lithologic reservoirs represented by Qi674 well reservoir, Lianmeng reservoir and Qinan 9-1 well reservoir, respectively, indicating that the area possesses the condition of forming certain size subtle reservoirs. According to the study of core, log and seismic facies, it is predicted that the low stand subaqueous fan sandbodies in the 3^rd member of Shahejie Formation on the western slope of Qinan sag and the slope break zone of the slope in Qibei sag would be the favorable areas in the later exploration; among which, the lithologic traps to the south of Kou 50 well and Zhuang 43 well fault block would firstly be selected as the exploration targets.

Characteristics and genesis of reef-bank facies reservoirs with dissolution pores in Ordovician Yijianfang Formation in Tahe oilfield

Zhang Tao, Yan Xiangbin, Wang Shuyi, Yu Maosheng

2004, 25(4):  462-466,471.  doi:10.11743/ogg20040418

Asbtract ( 807 )   PDF (6308KB) ( 760 )  

References | Related Articles | Metrics

The organic reef and bank facies, widely developed in Middle Ordovician Yijianfang Formation in Tahe oilfield, are characterized by point reefs and banks within the caronate platforms, and the reservoir spaces are mainly of microfissures and secondary dissolution pores. Vertically, characterized by their uneven distribution in various horizons, while laterally, as a whole, they appear to be well developed in the west and poor in the east. In addition, the permeable-storage spaces are heterogeneous in the reservoir intervals. The formation of secondary dissolution pores had been controlled by karstification of meteoric water during Caledonian or Early Hercynian, and then had been superimposed by late structural fracturing and deep-lying dissolution, of which late deep-lying dissolution to be the main a-gent. Organic acid and CO₂, generated from thermal degradation of source rocks and thermo-catalytic cracking of hydrocarbons in reservoirs, destabilized and dissolved the carbonates at depth. Thermal convection and circulation system, caused by temperature difference, would be the main dynamic force driving the fluid flow.

Reservoir space characteristics and evolution of the Palaeozoic reservoir rocks in Shuguang buried hills,Liaohe fault basin

Wei Xi, Zhu Yongjun, Zhao Guochun, Song Bairong, Wang Yunzhe

2004, 25(4):  467-471.  doi:10.11743/ogg20040419

Asbtract ( 755 )   PDF (5541KB) ( 502 )  

References | Related Articles | Metrics

The reservoir rocks in Shuguang buried hills, Liaohe fault depression are mainly composed of both sandstone and carbonate rocks. A large proportion of reservoir space is secondary, including vugs and fractures. In Shuguang buried hills the medium-high buried hills are characterized by the so-called "fracture development in upper part but vug development in lower part", that is, the tectonic fractures are common in the upper part of buried hills without so-lutional voids, whereas the large numbers of solutional voids most likely to occur in the lower part of buried hills. The development belt of fracture and secondary pores is also present in gentle buried hills, but its buried depth is deeper than that in medium-high buried hills. The distribution of reservoir rocks in buried hill is related to the following factors:(1) a vast amount of solution vug and fracture formed by crust uplift, compressional strike-slip orogenesis, weathering and denudation during the late Paleozoic-Mesozoic era; (2)new fissures formed by the progressively deep burial of reservoir rocks in Shuguang buried hills during the Cenozoic strike-slip extension; (3)redistribution and reworking of the existing pores and fissures in Shuguang buried hills due to the steady burial diagenesis of overlying strata.

Recent oil and gas exploration advance of Shengli oilfield

Li Pilong

2004, 25(4):  472-478.  doi:10.11743/ogg20040420

Asbtract ( 797 )   PDF (8408KB) ( 414 )  

References | Related Articles | Metrics

During recent years of the new century, Shengli oilfield Company has practised the strategy of resource expanding, insisted on the precept that exploration is the top of the most important things, and persisted in the exploration policy of keeping old prospect stable, intensifying the new area, laying equal stress of oil and gas, and realizing development, as well as the principle of the integration of inverstment, oil reserves, workload, cost and benefit, aimed at the positive circulation of exploration theory, target, well-site and oil reserves, gone step further in animating idea, speeded up theory construction, strengthened technology tackling, a number of new breakthroughs and advances have been achieved, while the result is the fact that oil reserves increase steadily, and the robust base has been laid for the following two years of the tenth five-year-plan.